If the apple costs 3 crowns and two apples cost 6 crows, then three apples should cost 9 crowns. This is an example of a proportional relation, in other words the cost increase equally for every apple.

Foto: Fredrik Enander

Imagine that you are going to bake some buns for 60 people instead of 20. You need to use the proportion of ingredients in order for the buns to taste like the recipe for 20 buns.

If you increase or decrease the number of portions in a recipe, this is an example of proportionality.